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Re: [PATCH] pass -no_pie to LINK_GCC_C_SEQUENCE_SPEC on darwin
On Sun, Dec 04, 2011 at 08:35:07PM +0000, Iain Sandoe wrote:
>
> On 4 Dec 2011, at 20:19, Jack Howarth wrote:
>
>> On Sun, Dec 04, 2011 at 08:18:32PM +0100, Jakub Jelinek wrote:
>>> On Sun, Dec 04, 2011 at 02:00:20PM -0500, Jack Howarth wrote:
>>>>>> at -m32/-m64 on x86_64-apple-darwin11 due to the -pie linker
>>>>>> default. Iain had wanted
>>>>>> to leave these in place to encourage boehm-gc to be fixed but I
>>>>>> doubt that is a realistic
>>>>>> goal in the near/middle term. Perhaps we could patch boehm-gc/
>>>>>> testsuite/lib/boehm-gc.exp
>>>>>> to pass -fno-pie on darwin (now that it is functional)?
>>>>>
>>>>> I think we should just find a way to add -fno-pie... Are there any
>>>>> flags that are added because we are doing gc that we can key off
>>>>> of?
>>>
>>> -f{pic,PIC,pie,PIE,no-pic} aren't option that should have any effect
>>> on how
>>> are binaries/shared libraries linked, these options control solely
>>> compilation. -shared, -pie or lack of these options determines how
>>> are
>>> things linked. So, either you should pass -no-pie or whatever
>>> linker option
>>> you need to generate position dependent binaries by default, unless
>>> -shared
>>> or -pie is specified, or you should add -no-pie or something
>>> similar, but
>>> IMHO it shouldn't be -fno-pie, that is a compilation option/too
>>> similar to
>>> them.
>>
>> Jakub,
>> This isn't really an option on darwin11 and later since the linker
>> defaults to
>> -pie and this results in warnings from the linker of the form...
>>
>> ld: warning: PIE disabled. Absolute addressing (perhaps -mdynamic-no-
>> pic) not allowed in code signed PIE, but used in _f from /var/tmp//
>> ccVNy9V9.o. To fix this warning, don't compile with -mdynamic-no-pic
>> or link with -Wl,-no_pie
>
> perhaps the question should be "why is this particualr code being built
> with non-default options?".
> x86 darwin code should default to fPIC - so someone must be passing -
> mdynamic-no-pic or -fno-PIC etc.
Iain,
I was only pointing out that we are in a unique situation when targeting
darwin11 and later since we are the only target currently creating PIE by
default. However unlike linux, darwin doesn't require or even encourage the
use of -fpie/-fPIE to do this but silently relies on the default -fPIC. Also, the
warning cited above was from gcc.dg/20020312-2.c which previously failed its
excessive error test since it passed -fno-pic which triggered the warning.
Jack
>
> (perhaps derived from the bootstrap usage of the "-mdynamic-no-pic"
> option - which suggests that this should be disabled for Darwin >= 11).
>
> Iain